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Where there’s water on Earth, there’s life. Is the same true on Mars?

NASA has found evidence of liquid water on Mars. Science correspondent Miles O’Brien joins Judy Woodruff to discuss the inevitable question: does this mean there could be some form of life on the red planet?

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  • JUDY WOODRUFF:

    Finally tonight: big news from outer space.

    NASA today announced that it has found evidence of liquid water on Mars, at least during certain seasons of the Martian year. The discovery was made through satellite images, which revealed darkly shaded streaks on slopes of craters and hillsides. They darken and lighten over time as water seeps across the surface, and then evaporates.

    For more on what it all might mean, I'm joined by science correspondent Miles O'Brien.

    Hello again.

  • MILES O’BRIEN:

    Judy, good to see you.

  • JUDY WOODRUFF:

    So, how do they know it's water, Miles? They don't — there hasn't been a human there to look at it. They're looking through satellites. What — how do they know?

  • MILES O’BRIEN:

    The HiRISE instrument, which is on the orbiting Mars Reconnaissance Orbiter, is a very sophisticated instrument and has the ability to do spectral analysis.

    So, it can actually look at how light moves through whatever is flowing there. And it gives unique signatures of water and in this case a lot of salt. It's the salt that is the key here, because Mars is cold and has an atmosphere which is almost nonexistent. So, the idea of water flowing there is hard to imagine.

  • JUDY WOODRUFF:

    But this flies in the face of what scientists thought for a long time, or have they been building up to this?

  • MILES O’BRIEN:

    Well, there is a huge body of evidence that Mars at one time was warm and wet, and we think probably a cushy birth for life.

    So, we have been looking for evidence of ancient life, fossils, for example. There has always been this thought that maybe the water is underneath in an aquifer. Could it somehow rise to the surface on certain occasions in certain ways? That's been a big question.

    They first spotted these streaks back in 2010. It sure looked like water. But what would keep it following? And the key was, they found these percolates, these salts in there. It's extremely salty water. Think of why do — how do we get snow off our roads in the winter? We use salt. Right?

  • JUDY WOODRUFF:

    Right.

    So, it's not the same. And let's talk about these streaks. We have got great images here to look at.

  • MILES O’BRIEN:

    They're spectacular.

    And this is essentially a cliff. And what you see is this — those dark streaks are the water, the briny water that percolate in fused water flowing downward. So, the question is, where did the water come from? Is it from an underground aquifer?

    It's kind of problematic, because it's starting at the top of the peak. That's unusual. Could it be somehow that there is a humidity component to it? Mars is very dry, but, under certainly circumstances, could there be what amounts to kind of dew or fog which is causing this? We don't know the answer to that yet.

  • JUDY WOODRUFF:

    But you keep using the word briny, very salty, so it's not like the water we have on Earth?

  • MILES O’BRIEN:

    You wouldn't want to drink it, for sure.

    But because it's so filled with the salt, it stays in liquid form where it would otherwise freeze. And so the key is, is it so salty that it can't support life? That's the real debate among scientists right now.

  • JUDY WOODRUFF:

    And what do they think? I mean, how are they thinking about that?

  • MILES O’BRIEN:

    Well, flowing water has been kind of the Holy Grail on Mars, and because wherever we look on this planet, where we see liquid water, we see life. It's a prerequisite for life as we know it.

    The question is, though, could this be water that sustains life? And could — when you think about salt, it was used as a preservative for a long time on voyages, because it kills microbes. So, there might be so much salt there that there is nothing living there.

    But where is the water coming from, and could it be fresher and could it thus sustain life?

  • JUDY WOODRUFF:

    So, how do they do further investigation?

  • MILES O’BRIEN:

    Well, I think it's going to beg for a mission, you know?

    And I think NASA will start thinking about the architecture for a mission. Let's go to a place — it's very difficult to get there because it's on these cliffs. How would you gather up that water? Or would it be smarter to try to find a place where it's a little more accessible, maybe go down to the aquifer beneath, drill down, and see if there are some microscopic Martians there. Who knows?

  • JUDY WOODRUFF:

    Who knows?

    It's fascinating, Miles, but for those people who are watching and saying, how does it really matter? There's water on Mars. Are we ever really going to really get there to find out?

  • MILES O’BRIEN:

    I think it's a question worth asking. Are we alone in the universe is a good question.

    And this — we have looked at our neighbor and we are getting closer and closer by hunting after the water to possibly finding evidence of life, ancient or maybe existing. And how exciting would that be? The next second question is, though, is it a second genesis? Or is it — Mars and Earth have been swapping…

    (CROSSTALK)

  • JUDY WOODRUFF:

    Another form of human…

  • MILES O’BRIEN:

    Exactly, or we could be Martians.

    (LAUGHTER)

  • JUDY WOODRUFF:

    Or we could have come from there.

  • MILES O’BRIEN:

    Exactly.

  • JUDY WOODRUFF:

    And this is what Earth looked like.

  • MILES O’BRIEN:

    Exactly.

  • JUDY WOODRUFF:

    But how excited — I read today that scientists are debating. How excited are they about this, the folks you talk to?

  • MILES O’BRIEN:

    This is Holy Grail kind of stuff. It's great science.

    It puts them in a space where they can start making an argument for missions that look beneath the surface. And it's what this steady stream of NASA and European and other missions to Mars have been all about, following the water, kind of a divining rod, if you will, a high-tech divining rod, and hoping at the end that the pot of gold will be maybe microscopic life.

  • JUDY WOODRUFF:

    It's just extraordinary. I mean, the pictures are extraordinary.

  • MILES O’BRIEN:

    Well, it literally puts you in another place, doesn't it? And it's spectacular to think we have the kind of imagery that gets us that level of detail on a satellite that's been orbiting that planet.

  • JUDY WOODRUFF:

    Miles O'Brien, every time you come here, we have another surprise.

  • MILES O’BRIEN:

    Yes. It's fun.

  • JUDY WOODRUFF:

    Thank you.

  • MILES O’BRIEN:

    You're welcome, Judy.

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